RecQL4 cytoplasmic localization: implications in mitochondrial DNA oxidative damage repair.
RecQL4 cytoplasmic localization: implications in mitochondrial DNA oxidative damage repair.
复制标题
DOI：
10.1016/j.biocel.2012.07.016
复制
发表时间：
2012-11
影响因子：
4
通讯作者：
Zhao, Yongliang
中科院分区：
文献类型：
--
作者：
Chi, Zhenfen;Nie, Linghu;Peng, Zhao;Yang, Qiong;Yang, Kuan;Tao, Jiahai;Mi, Yang;Fang, Xiangdong;Balajee, Adayabalam S.;Zhao, Yongliang
关键词：
RecQL4是人类五种RecQ解旋酶之一，对基因组的稳定性至关重要，当RecQL4突变时会导致人类的过早衰老表型。与其他人类RecQ解旋酶不同，RecQL4在细胞核和细胞质中都有发现。虽然核定位信号(NLS)和N末端的保留结构域负责RecQL4的核定位，但其细胞质定位的信号基本上是未知的。在本研究中，在RecQL4的C末端发现了两个功能性核输出信号(Ness；pNES2和pNES3)。PNES2的缺失显著降低了RecQL4的胞质定位。值得注意的是，只有在功能性pNES2存在的情况下，在RecQL4的C末端添加泛素化尾巴才能显著丰富RecQL4的细胞质部分。免疫荧光研究表明，胞质RecQL4定位于线粒体。与其线粒体定位一致，RecQL4在维持线粒体DNA(MtDNA)拷贝数方面具有调节作用。异位表达的RecQL4使HEK293细胞mtDNA拷贝数增加，而RecQL4基因敲除后U2OS细胞mtDNA拷贝数明显减少。此外，在RecQL4缺陷的人成纤维细胞和RecQL4抑制的癌细胞的线粒体中，观察到线粒体超氧化物生成水平显著增加，对DNA氧化损伤的修复能力显著降低。这些数据有力地表明了RecQL4在线粒体稳定性和功能中的调节作用。总之，我们的研究表明，NES介导的RecQL4输出到细胞质对于维持线粒体基因组的稳定性是必不可少的。
RecQL4, one of the five human RecQ helicases, is crucial for genomic stability and RecQL4 when mutated leads to premature aging phenotypes in humans. Unlike other human RecQ helicases, RecQL4 is found both in the nucleus and the cytoplasm. While the nuclear localization signal (NLS) and the retention domain at the N-terminus are responsible for the nuclear localization of RecQL4, the signal for its cytoplasmic localization is essentially unknown. In this study, two functional nuclear exporting signals (NESs; pNES2 and pNES3) were identified at the C-terminus of RecQL4. Deletion of pNES2 drastically diminished the cytoplasmic localization of RecQL4. Strikingly, addition of ubiquitination tail at the C-terminus of RecQL4 substantially enriched the cytoplasmic fraction of RecQL4 only in the presence of functional pNES2. Immunofluorescence studies revealed that the cytoplasmic RecQL4 was localized in mitochondria. Consistent with its mitochondrial localization, a regulatory role for RecQL4 in the maintenance of mitochondrial DNA (mtDNA) copy number was demonstrated. Elevation of ectopic expression of RecQL4 increased the mtDNA copy number in HEK293 cells while RecQL4 knock down markedly decreased the mtDNA copy number in U2OS cells. Additionally, a substantially increased level of mitochondrial superoxide production, and a markedly decreased repair capacity for oxidative DNA damage were observed in the mitochondria of both RecQL4 deficient human fibroblasts and RecQL4-suppressed cancer cells. These data strongly suggest a regulatory role for RecQL4 in mitochondrial stability and function. Collectively, our study demonstrates that NES-mediated RecQL4 export to the cytoplasm is essential for the maintenance of mitochondrial genome stability.
登录
查看更多内容
影响因子：
3.8
作者：
Rossi ML;Ghosh AK;Kulikowicz T;Croteau DL;Bohr VA
通讯作者：
Bohr VA
DOI：
10.1073/pnas.95.12.6887
发表时间：
1998-06-09
影响因子：
11.1
作者：
Marciniak, RA;Lombard, DB;Guarente, L
通讯作者：
Guarente, L
影响因子：
4
作者：
Petkovic, M;Dietschy, T;Stagljar, I
通讯作者：
Stagljar, I
影响因子：
19
作者：
Kutay, U;Güttinger, S
通讯作者：
Güttinger, S
影响因子：
4.8
作者：
Sage, Jay M.;Gildemeister, Otto S.;Knight, Kendall L.
通讯作者：
Knight, Kendall L.